now, scientist stephen hawking is tackling some of the toughest questions.tist stephen hawking do aliens really exist? is there a god? our nick watt sat down for a require interview. good morning, nick. >> reporter: this is it. "the grand design." i'm reading it slowly, i admit. and in it, hawking and his co-author make a very, very bold statement. apparently our universe was created from nothing. hawking writes in his book, it is not necessary to invoke god to light the blue touch paper and set the universe going. can you prove that god does not exist? or just that the universe could have been created without one? >> one can't move that god doesn't exist. but science makes god unnecessary. the laws of physics can explain the universe, without the need for a creator. >> reporter: because there is a law such as gravity, he writes, the universe can and will create itself from nothing. there was, hawking says, no hand of god. when will the human race, do you think, meet its end? are we destined to fail? >> life in the universe will cease to be possible when the universe becomes cold, dark a